Where do I get the tail boom?

The tail boom is a fiberglass tapered boom — it is not included in the short kit (wood parts only) and there is no commercial replacement currently available. Builder options are: (1) source an original Airtronics boom from the secondary RC market (eBay, RC Groups classifieds); (2) fabricate one from fiberglass cloth and epoxy over a tapered mandrel per the plan; or (3) use a tapered fishing pole blank as a substitute — a technique documented in the RC soaring community.

What's the finished size and weight of the Grand Esprit?

134" wingspan, 1,100 sq in of wing area. Finished flying weight is 60–70 oz (3.75–4.4 lb) — exceptionally light for a 134-inch sailplane. These figures come from the original Airtronics Grand Esprit specification.

Kit Cutters Completion Guide

Airtronics Giant-Scale Short Kit — Original & Sinclair 3014 Wing

134" Grand Esprit

Lee Renaud's legendary giant sailplane — the competition standard of the 1970s and 1980s, available in Original and Improved Sinclair 3014 Wing versions.

Buy the Kit — $132.00 See Everything You Need

Wingspan

134 in

Wing Area

1,100 sq in

Flying Weight

60–70 oz

Airfoil

Eppler

Tail

V-tail

Power

None — pure glider

Skill

Advanced

A Legend, Faithfully Cut

Lee Renaud designed the Airtronics Grand Esprit and introduced it on the cover of RCM magazine in July 1973. It was the first multi-task competition sailplane to be commercially kitted — introducing spoilers and a V-tail to the RC soaring scene at a time when those features were considered advanced. Through the late 1970s and 1980s, the Grand Esprit dominated the NSS (National Soaring Society) competition circuit. One example placed first at both the WRAM and Toledo shows and is now in the AMA's National Model Aviation Museum.

Kit Cutters offers this in two versions: the Original Standard Wing from the 1974 Airtronics plan, and the Improved Sinclair 3014 Wing with corrected rib templates by Alan Sinclair. The fuselage, tail boom, and all other components are identical between versions. This guide covers both.

134-inch Airtronics Grand Esprit giant-scale RC sailplane in flight

Two Wing Versions — Choose Before You Order

Original Standard Wing

The original 1974 Airtronics rib geometry. Faithful to the historic kit. Plans from the Outerzone PDFbitmap version (oz9015).

Download Original Plans (Free)

⬇ Original Wing Pack List

Improved Sinclair 3014 Wing

Redesigned by Alan Sinclair with corrected rib templates and updated geometry. The Sinclair plans include both original and 3014 rib stencils — the second plan page shows the 3014 build specifically.

Download Sinclair 3014 Plans (Free)

⬇ Sinclair 3014 Pack List

What's in the Box?

Included in the Short Kit

Precision laser-cut wood parts only — ribs, formers, shaped parts
Wing rib set (Original or Sinclair 3014 — per version ordered)
Fuselage pod formers and shaped parts
V-tail surface structure parts

Required Separately

Plans (free from Outerzone.co.uk — oz9015)
Fiberglass tapered tail boom (not included — no commercial source)
Wing spars, sheeting, spruce, and stick balsa
V-tail mixer (mechanical or radio mixing)
Towhook, pushrods, horns, hardware, covering
No engine, no motor, no landing gear — pure sailplane

Everything Else You Need to Complete This Kit

The Grand Esprit is a pure sailplane — no engine, no cowl, no landing gear. The accessory list is shorter than any warbird in this catalog, with one significant exception: the fiberglass tapered tail boom, which has no current commercial source.

Tail Boom

No commercial source — see options

The Grand Esprit uses a fiberglass tapered tail boom — not included in the short kit. The original Airtronics kit supplied a yellow-tone fiberglass tapered boom. No commercial replacement is currently available. Three options are documented in the builder community:

Option 1 — Secondary market	Original Airtronics tail boom occasionally appears on eBay and RC Groups classifieds. Search "Airtronics Grand Esprit tail boom" or "Airtronics Grand Esprit parts."	Secondary R/C Market
Option 2 — Fishing pole blank	Tapered fishing pole blanks (fiberglass or graphite composite) are used by RC soaring builders as tail boom substitutes. Dimensions per plan — taper must match the plan specification.	Fishing / outdoors retailers
Fiberglass cloth	Woven fiberglass cloth for tail boom layup — use over a tapered mandrel per plan dimensions	Aircraft Spruce
Fiberglass adhesive (epoxy)	Epoxy resin for fiberglass tail boom fabrication — laminating grade, mixed per manufacturer ratio	Aircraft Spruce

Plan ahead — The tail boom is the longest-lead item in this build. Source or fabricate it before construction begins. The boom dimensions are shown on the plan — confirm your source matches the plan specification before committing.

Flight Controls — V-Tail Mixer

Required

The Grand Esprit uses a V-tail (butterfly tail) with elevons. A mixer is required to convert separate elevator and aileron inputs to the two V-tail surfaces. The original kit used a mechanical Vector Director II mixer — modern builders use radio mixing instead.

Radio mixing (recommended)	Any modern transmitter with V-tail or elevon mixing. Program V-tail mix and adjust throws to plan spec. No mechanical mixer needed.	Builder's existing transmitter
Mechanical mixer (original)	Vector Director II — occasionally found on secondary market. Obsolete — radio mixing is simpler and more precise for modern setups.	Secondary RC market

Launch System

Hi-Start, winch, or slope

Hi-Start (bungee)	Surgical tubing Hi-Start — the launch method Lee Renaud invented. 50–100 ft of surgical tubing with a 200–300 ft towline. Standard for field flying.	Chief Aircraft / specialty
Electric winch	Club electric winch — the preferred launch for competition. Requires a field with winch infrastructure.	Club facility
Slope soaring	Suitable for slope sites with sufficient lift — hand launch from the slope.	No purchase needed
Adjustable towhook	Heavy-duty adjustable towhook — required for Hi-Start and winch launch. Position per plan CG notes.	Chief Aircraft / specialty

Servos

2–3 channels

V-tail surfaces (×2)	2× 50–65 oz-in ball bearing — one per V-tail surface (elevon mixing in radio)	Builder preference
Spoilers (optional)	1× 50 oz-in if spoilers fitted — shown on plan as optional	Builder preference

Minimum 2 channels (V-tail elevons via mixer). Add a third for spoilers if fitted. The Grand Esprit has no ailerons — roll is controlled through the V-tail mixing.

Hardware & Pushrods

Pushrods	Standard nylon or steel RC pushrods — the original kit included a full hardware set. Buy a selection of DuBro or Sullivan pushrods sized per the plan.	Dubro / Sullivan
Control horns & clevises	Nylon or metal control horns and ball-link/clevis set — sized per plan	Dubro
Hinge material	Full-span hinges for V-tail surfaces per plan — plan specifies full-span hinge type	Dubro / specialty
Wing spars	Double hardwood spars with plywood webbing on the inboard panel — per plan specification	Specialty balsa supplier
Belly skid	Belly skid per plan — no landing gear on this model	Per plan

Covering & Finishing

Covering	Iron-on film (Monokote, Oracover, or Ultracote). The classic Grand Esprit color scheme is white fuselage pod with high-visibility wing tips — red, white, and blue is the most documented competition scheme.	Chief Aircraft / specialty
Canopy	Vacuum-formed canopy (butyrate) — included in the original Airtronics kit; source from secondary market or vac-form per plan. Occasionally available as repop.	Secondary RC market
Instrument housing	Vacuum-formed instrument housing — included in original kit; source from secondary market or substitute with a simple hatch cover.	Secondary RC market / per plan

Detailed Specifications

Wingspan	134 in
Wing area	1,100 sq in
Flying weight	60–70 oz (3.75–4.4 lb)
Airfoil	Eppler
Wing construction	Double hardwood spars, plywood webbing (inboard), geodetic ribs, elevons
Tail	V-tail (butterfly) — elevon mixing required
Boom	Fiberglass tapered tail boom — not included, no commercial source
Fuselage	Pod-and-boom — plywood pod sides, 1/2" balsa floor, 1/4" plywood keel insert
Gear	Belly skid only — no landing gear
Launch	Hi-Start, electric winch, or slope
Spoilers	Optional — shown on plan; significantly shortens landing
Min. radio channels	2 (V-tail mix) + optional spoiler channel
Wing versions	Original Standard Wing / Improved Sinclair 3014 Wing

Specs from the original Airtronics Grand Esprit specification and RCM 1975 review. The Sinclair 3014 wing uses revised rib templates with corrected geometry — fuselage and all other specs are identical. Plans free from Outerzone.co.uk, plan ID oz9015.

Lee Renaud & Airtronics

Lee Renaud founded Airtronics, Inc. in 1971 and the Grand Esprit was his landmark design. He invented the surgical tubing Hi-Start — the standard field launch method still in use today — and the Grand Esprit was the first multi-task competition sailplane to be commercially kitted. His later designs, the Aquila, Aquila Grande, and Aquila XL, built on the Grand Esprit's legacy. The AMA inducted Renaud into its honor rolls for his contributions to model aviation.

Plans: free from Outerzone.co.uk (oz9015) · Original and Sinclair 3014 versions both available

Original Plans (Outerzone) Sinclair 3014 Plans (Outerzone)

The Build Journey

The Grand Esprit is described in the original RCM review as building "easier than anticipated" with "nothing unusual" about the radio installation. The geodetic wing construction is distinctive — both time-consuming and satisfying — and the pod-and-boom structure is clean and well-documented. Treat these ranges as a rough sense of scope.

Where a short kit saves you time

The Grand Esprit's geodetic wing ribs are its most distinctive and time-consuming structural element — intricate cross-members that must all be individually cut and fitted. A Kit Cutters short kit delivers those ribs laser-cut and labeled, removing the most tedious stage of the build.

Plans only (hand-cut)

Trace and cut every geodetic rib, former, and pod part from raw stock using the plan templates.

more time, lower part cost

Short kit (laser-cut)

All ribs and formers arrive laser-cut. The most complex cutting task in the build — done.

less time, cleaner fit

The four stages of assembly

Stage 1: Fuselage Pod Assembly

The plywood pod sides with balsa floor and plywood keel insert.

Build the plywood pod sides
Fit keel insert and floor
Install towhook and nose ballast bay
Fit the tail boom to the pod rear

Stage 2: Wing Assembly

Geodetic ribs over double hardwood spars — the heart of the Grand Esprit build.

Build the main spar box
Fit geodetic ribs (laser-cut from short kit)
Install elevon hinges and control linkages
Sheet and cap the inboard panel

Stage 3: V-Tail Assembly

The V-tail surfaces — the feature that made the Grand Esprit distinctive in its era.

Build the two V-tail panels
Install full-span hinges
Connect elevon control rods through the tail boom
Verify V-tail angle per plan

Stage 4: Systems & Final Assembly

Radio, covering, and pre-flight.

Install servos and radio gear in pod
Program V-tail mix in transmitter
Cover with iron-on film
Balance to plan CG and adjust towhook position

Frequently Asked Questions

The Original Standard Wing uses the rib geometry from the original 1974 Airtronics plan. The Improved Sinclair 3014 wing was redesigned by Alan Sinclair with corrected rib templates and updated geometry. The fuselage, tail boom, and all other components are identical — only the wing ribs differ. The Sinclair 3014 plans include both rib stencils; the second plan page shows the 3014 build specifically.

The tail boom is a fiberglass tapered boom — not included in the short kit and no commercial replacement is currently available. Builder options: (1) source an original Airtronics boom from eBay or RC Groups classifieds; (2) use a tapered fishing pole blank (a documented technique in the RC soaring community); (3) fabricate one from fiberglass cloth and epoxy over a tapered mandrel per the plan dimensions.

The Grand Esprit uses a V-tail (butterfly tail) with elevons — combined elevator and aileron function on the two V-tail surfaces. The original kit included a mechanical Vector Director II V-tail mixer. Modern builders use radio V-tail mixing, which requires a transmitter with V-tail or elevon mixing capability.

Both plan versions are free downloads from Outerzone.co.uk (plan ID oz9015). The Original plan is the PDFbitmap version. The Sinclair 3014 is the PDFvector version — the second page shows the 3014 wing build. Plans are free — community-preserved from the original Airtronics kit.

No. The Grand Esprit is a pure sailplane — no engine, no motor. It is launched by Hi-Start (bungee), electric winch, or aerotow. Slope soaring is also suitable. No power system, fuel tank, ESC, or battery is needed.

The Grand Esprit was one of the dominant competition sailplanes of the 1970s and 1980s NSS circuit. Multiple WRAM and Toledo show champions flew this design. One example placed first at both shows and is now in the AMA's National Model Aviation Museum in Indiana. It was the first multi-task sailplane to be commercially kitted.

The Airtronics Grand Esprit was designed by Lee Renaud, founder of Airtronics, and first appeared on the cover of RCM magazine in July 1973. It was the first multi-task competition sailplane to be commercially kitted — introducing spoilers and a V-tail to RC soaring — and dominated competition through the late 1970s and 1980s.

134" wingspan, 1,100 sq in of wing area. Finished flying weight is 60–70 oz (3.75–4.4 lb) — exceptionally light for a 134-inch sailplane, which is one of the reasons it soars so well. These figures come from the original Airtronics Grand Esprit specification.

Ready to Build Your Grand Esprit?

Buy the 134" Grand Esprit Kit — $132.00

Prices and availability are subject to change — verify on each vendor's site before ordering. Kit Cutters supplies laser-cut wood parts only; plans are free from Outerzone.co.uk. The tail boom is not included in the short kit — see the Tail Boom section above for sourcing options.

Premium laser-cut short kits for large-scale and giant-scale radio-controlled aircraft builders. USA-based quality craftsmanship for serious hobbyists.